Page 699 of 796
12-4
Spare Tire & Winch Assembly
- Spare tire specification added (same as one fitted to vehicle with standard wheel and tire)
Wheel assembly
16 inch (6.5JX16) 17 inch (7.0JX17)
2WD 4WD 2WD 4WD
225/65R16 235/60R17
- 16 inch wheel design changed (same as before for tire size)
- 17 inch wheel specification added (235/60R17 tire)
2. CHANGES
Wheel tire design changed and specification added ▶
With spare tire ▶
Spare tire
Winch assembly
Page 700 of 796
12-54170-01
1. OVERVIEW
A radial tire uses a cord angle of 90 degrees. That is, the cord material runs in a radial or direct line
from one bead to the other across the tread. In addition, a radial tire has a belt overwrap under the
tread surface to provide greater structural stability. The belt overwrap of a radial tire distortion while the
radial structure enables high speed driving.
Tire supports the weight of the vehicle, reduces the impact from the road and at the same time,
transmits the power to propel, brake and steer on the road. It also functions to maintain a
vehicle’s movement. In order to complete such tasks, a tire must be structured to be a resilient
vessel of air.
There is wear limit mark on the tire, which protrudes as a strip shape located approximately 1.6 mm
from the groove bottom. This wear limit mark is not seen from the outside so there is additional
"▲" mark on the shoulder to let the driver find the wear mark easily. To measure the tire groove
depth, measure at any point other than the point which has a wear limit mark.
The tire is worn unevenly according to the driver's driving habit, improper servicing, low tire inflation
pressure, changed tire location, etc.
1) Structure of Tire
Tread
This thick layer of rubber provides the interface
between the tire and the road. Wear-resistant
rubber is used to protect the carcass and belt
against fractures and impacts and to deliver a
long driving life.
Shoulder
Located between the tread and sidewall, the
shoulder rubber is the thickest so that the
design must allow for the easy diffusion of heat
generated within the tire while driving.
Sidewall
The part between the shoulder and bead, the
flexible sidewall protects the carcass and
enhances the ride. A tire’s type, size,
structure, pattern, manufacturing company,
product name and various characters are
indicated here. Bead
The bead attaches the tire to the rim and wraps
the end of the cord fabric. Comprised of the bead
wire, core, flipper and other parts, the bead is
generally designed to be slightly tight around the
rim so that in the case of a sudden drop in
inflation pressure, the tire will not fall off the rim.
Carcass
As the most important framework of a tire, the
entire inner layer of cord fabric is called the
carcass. The carcass acts to support air
pressure, vertical load and absorb shocks.
Valve
Belt
Bead core
Page 704 of 796
12-94170-01
If weight is not equally distributed around the wheel, unbalance centrifugal force by the wheel rotation
produces vibration. As the centrifugal force is produced proportional to the square of the rotating
speed, the wheel weight should be balanced even at high speed. There are two types of the tire and
wheel balancing: static and dynamic. Abnormal vibration may also occur due to unbalanced rigidity or
size of tires.
1) Static Balance
When the free rotation of the wheel is
allowed, the heavier part is stopped on the
bottom if the wheel weight is unbalanced
and this is called "Static Unbalance". Also,
the state at which tire's stop position is not
same is called "Static Balance" when the
wheel is rotated again. If the part A is heavie
r
as shown in the figure 1, add the balance
weight of a weight corresponding to
unbalanced weight from B to A to maintain
the static balance. If the static balance is not
maintained, tramping, up and down vibration
of the wheels, occurs.
2) Dynamic Balance
The static unbalance of the wheel creates
the vibration in the vertical direction, but
the dynamic unbalance creates the
vibration in the lateral direction. As shown
in the figure 2 (a), if two parts, (2) and (3),
are heavier when the wheels are under the
static balance condition, dynamic
unbalance is created, resulting in shimmy,
left and right vibration of the wheels, and
the torque Fxa is applied in the axial
direction. To correct the dynamic
unbalance, add the balance weight of a
same weight for two points of the
circumference of the rim, A and B, as
shown in the figure 2 (b), and apply the
torque in the opposite direction to the
torque Fxa to offset in order to ensure
smooth rotation of the wheel.
Center
a
a
Fxa
Fxa F
F
A
B
(a)(b)
[Figure 1]
[Figure 2]
3. WHEEL BALANCE
